What are vitamins?

Vitamins are an essential part of our diet. Without an
adequate amount of vitamins, a deficiency will occur. Vitamins are naturally
found in the foods that we consume and are also found in supplements. A
well-balanced diet is often enough to meet the vitamin needs of healthy
individuals. When a supplementation is needed, it is important to know how much
you need to take and the best way to take it.

Vitamin A

Vitamin A has many important functions in your body. It helps
regulate your immune system, helps form and maintain healthy teeth, skin, and
tissue, it produces the pigments in the retina of the eye, and promotes good
vision. A deficiency in this vitamin can lead to problems with any of these. The
vitamin A found in plants serves different functions than the vitamin A found in
animals. The animal sources of vitamin A are liver, whole milk, and fortified
foods, and the plant sources include colorful fruits and vegetables like
carrots, spinach, kale, and cantaloupe.

The recommended dietary allowances (RDA)
for vitamin A are listed as international units (IU) of retinol activity
equivalents (RAE). This is done to account for the different actions of both
forms of vitamin A.

Going above the RDA for vitamin A can initially cause nausea, vomiting,
irritability, drowsiness, altered mental status, anorexia, abdominal pain,
blurred vision, muscle pain with weakness, and/or headache. Over time, this can
lead to hypervitaminosis A or vitamin A toxicity. The harmful effects of this
are birth defects, reduced bone density that may result in osteoporosis, central
nervous system disorders, and liver abnormalities.